Apparatus, such as laminators, for applying photoresist material to opposite sides of a rigid board in the manufacture of printed wiring boards are well known in the art. Typically, the photoresist material, having a preselected width, is drawn from rolls and laminated to both sides of a plurality of rigid boards being fed in sequence between two sheets of the material. Thereafter, the individual rigid boards, which are connected together by a finite length of the material, must be separated by severing the material between the individual rigid boards. This procedure is time consuming and results in the formation of small particles and slithers of the material which frequently affects the efficient manufacture of and the subsequent utilization of the manufactured printed wiring boards. Moreover, the excess photoresist material between the boards must be discarded thus creating a waste of the material.
U.S. Pat. No. 3,658,629, which issued to L. P. Cramer et al., discloses a laminator which will cut sheets of the photoresist material and laminate them to panels within a defined perimeter. A pair of spaced drums each receive and vacuumly grip the leading section of photoresist material extending from two respective supply rolls. As each leading section of photoresist material is fed from the respective roll to the respective drum, a vacuum holds the material in place on the surface of the drum while a cutter operates at a predetermined location relative to the drum to sever the leading section from the roll to form a sheet of the photoresist material in a desired length. The leading edge of each sheet is then pressure sealed to a leading edge of the respective opposite sides of the panel. The panel is then moved through the laminator between, but spaced from, the drums as the sheets of material are pulled from the respective drums. As the panel emerges from between the drums, the sheets of material are held with the panel by the pressure seal along the leading edge and the natural adhesion characteristics of the resist material. Thereafter, the panel is fed between curing rollers to permanently secure the severed sheets of photoresist material to opposite sides of the panel.
During the latter stages of transfer of the sheets from the drums to the panel, the trailing portions of the sheets are released by the drums but are not in intimate contact with the moving panel due to the fact that the drums are spaced from the panel. Even though the sheets have been stretched between the drums and the moving panel, the trailing portions of the sheets are no longer held and would tend to assume a condition other than wrinkle-free as the trailing portions pass through space from the drums to the panel. While the leading portions of the sheets would appear to be secured to the panel in a wrinkle-free condition after passing between the curing rolls, it appears that the trailing portions of the sheets would tend to assume a less than wrinkle-free condition prior to passing between the curing rolls and, consequently, would be secured to the panel in that less-than-desired condition. Consequently, there is a need for a method of and apparatus for applying photoresist material to the rigid panel which precludes the development of wrinkles in the entire sheet of material as the sheet is being laminated to the panel.